Pregnancy is unquestionably a major milestone in a woman’s life. During gestation, her body shape noticeably changes, but the invisible structural and cognitive changes in her brain are more striking. Some of those neurobiological changes are short-term, while others are long-lasting, well beyond delivery, and even into old age.
Physiological changes during pregnancy are extraordinary. The dramatic increases in estrogen, progesterone, and glucocorticoids help maintain pregnancy, ensure safe delivery of the baby, and trigger maternal behavior. However, other important changes also occur in the mother’s cardiac output, blood volume, renal function, respiratory output, and immune adaptations to accommodate the growth of the fetus. Gene expression also occurs to accomplish those changes, and there are lifelong repercussions from those drastic physiological changes.
During pregnancy, the brain is exposed to escalating levels of hormones released from the placenta, which the woman had never experienced. Those hormones regulate neuroplasticity, neuroinflammation, behavior, and cognition.
Structural brain changes1-6
Brain volume declines during pregnancy, reaching a nadir at the time of parturition. However, recovery occurs within 5 months after delivery. During the postpartum period, gray matter volume increases in the first 3 to 4 weeks, especially in areas involved in maternal behavior, including the amygdala, prefrontal cortex, and hypothalamus. Hippocampal gray matter decreases at 2 months postpartum compared to preconception levels, and reductions can still be observed up to 2 years following delivery. Gray matter reductions occur in multiple brain regions involved in social cognition, including the superior temporal gyrus, medial and inferior frontal cortex, fusiform areas, and hippocampus. Those changes correlate with positive maternal attachment. It is noteworthy that neural activity is highest in areas with reduced gray volume, so a decline in brain volume is associated with enhanced maternal attachment. Interestingly, those changes occur in fathers, too.
Childbearing improves stroke outcomes in middle age, but body weight will increase. The risk of Alzheimer’s disease increases with a higher number of gestations, but longevity is higher if the pregnancy occurs at an older age. Reproduction is also associated with shorter telomeres, which can elevate the risk of cancer, inflammation, diabetes, and dementia.
Cognitive changes7-10
The term “pregnancy brain” refers to cognitive changes during pregnancy and postpartum; these include decreased memory and concentration, absent-mindedness, heightened reactivity to threatening stimuli, and a decrease in motivation and executive functions. After delivery a mother has increased empathy (sometimes referred to as Theory of Mind) and greater activation in brain structures involved in empathy, including the paracingulate cortex, the posterior cingulate, and the insula. Also, the mirror neuron system becomes more activated in response to a woman’s own children compared to unfamiliar children. This incudes the ventral premotor cortex, the inferior frontal gyrus, and the posterior parietal cortex.
Certain forms of memory are impaired during pregnancy and early postpartum, including verbal free recall and working memory, as well as executive functions. Those are believed to correlate with glucocorticoids and estrogen levels.
Continue to: The following cognitive functions...